The present invention relates in general to power distribution. More, specifically, the present invention provides a system and method for controlling power distribution to multiple loads. It provides individual control from a central location of widely dispersed loads whereby all necessary communications may be conducted over existing telephone lines and power distribution lines.
The desirability of load management is already recognized by utility companies. One of the general advantages of load management is conservation of resources while effectively meeting the existing demand for power. An important design constraint for a utility system is that it be able to meet peak load demand conditions. Load management concepts permit lowering of peak load demands without adversely affecting the overall "quality" of service. Since the supply of power necessary to meet demand is effectively lowered by load management techniques, resources both natural and capital may enjoy considerable savings.
While meeting power requirements, residential, commercial or any other type, with minimum necessary resources has distinct rewards, it is a goal not easily obtained. Load management techniques offer help in this regard, but application of any substantial changes in a macro-system such as a utility power distribution system generates numerous problems. A main problem is that a typical utility distribution system encompasses a myriad of widely dispersed individual loads and considerable distribution equipment. Accordingly, individual control of each such load potentially involves considerable communications and switching equipment and manpower requirements.
Communicating a decision to shed a particular load and executing that decision is the essential problem. Prior techniques have included radio transmission equipment to communicate load shedding decisions to the various relatively remotely located loads. This has numerous disadvantageous in that "dead spots" will naturally occur in a radio-link communications system as well as interference thereby rendering the system inoperative in certain areas. Additionally, that mode of communication does not lend itself to simultaneous individual control of numerous loads inasmuch as only a finite amount of bandwidth space is available for the respective radio communications, and this space would be rapidly consumed in assigning channels for the various loads.
Additionally, cost factors are of relative importance in a system where such large numbers of equipment might be necessary. That is to say, as complexity of a communication and switching system rises, the total cost of such of a system goes up sharply due to the large number of pieces of equipment necessary to accomplish all of the communicating and switching.
Other proposals to solve this large-scale communications problem have sought to transmit modulated information signals through existing power distribution lines. Again, the complexity and cost of the necessary transmitters and receivers have rendered such systems less than totally desirable for such large-scale operations.